Web3/nodejs 无法在 Pancakeswapv2 上使用 swapExactTokensForEth

Question

我在 BSC 上为 BNB 出售代币 BUNNY 时遇到了实际问题。这是我所知道的有效方法

查看配额显示我已获准在 PCSv2 路由器上交易 BUNNY
增加津贴也有效
花费 BNB 购买 BUNNY 也有效（swapExactETHforTokens）
在 BSC 扫描上手动写入合约也可以

不起作用的是 swapExactTokensForETH - 它会消耗一些 gas 但会抛出： “传输失败”...原因：'transaction failed'，代码：'CALL_EXCEPTION' 这是来自 node.js 脚本的失败交易 https://bscscan.com/tx/0x55d45e5f1e937fcd55294fa3e4d8c4c24d9c578b7ba8361fb12b2a017d7e7a4b

现在我所做的所有研究都表明这是因为我需要批准支出者 - 我已经这样做了...我怎么知道？好吧，我写的函数说它很好，直接查询 BUNNY 另一件奇怪的事情是这完美地工作（没有额外的批准） - 见截图

BSCScan Write Contract that works

这是 BSCscan 写入路由合约部分的成功交易 https://bscscan.com/tx/0xc8d2b999c08cef6ecceecf4bc5d6242bcd43571164016a8372bbf0c02d1a6185

如果有人能弄清楚为什么会抛出这个错误，那将是一个巨大的帮助 tyvm 提前这是代码：

const ethers = require('ethers');
const Web3 = require('web3');
const abi = require('human-standard-token-abi');
const {ChainId, Token, TokenAmount, Fetcher: v2Fetcher, Pair, Route, Trade, TradeType, Percent} = require('@pancakeswap-libs/sdk-v2');

const {JsonRpcProvider} = require("@ethersproject/providers");
const url = 'https://bsc-dataseed1.binance.org/';
const provider = new JsonRpcProvider('https://bsc-dataseed1.binance.org/');
const web3 = new Web3(url);

const secretKey = process.env.SECRETKEY;
const walletAddress = process.env.WALLETADDRESS;
const wallet = ethers.Wallet.fromMnemonic(secretKey);
const account = wallet.connect(provider);

const pcsRouterV2 = Web3.utils.toChecksumAddress('0x10ED43C718714eb63d5aA57B78B54704E256024E'); //v2 router
const routerV2 = new ethers.Contract (pcsRouterV2, [
    'function getAmountsOut(uint amountIn, address[] memory path) public view returns (uint[] memory amounts)',
    'function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline) external payable returns (uint[] memory amounts)',
    'function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external returns (uint[] memory amounts)',
    'function swapExactTokensForTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external returns (uint[] memory amounts)'
    ], account );

const bunnyAddress = Web3.utils.toChecksumAddress('0xc9849e6fdb743d08faee3e34dd2d1bc69ea11a51');
const wbnbAddress = Web3.utils.toChecksumAddress('0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c'); // WBNB

const gasApprovalLimit = 100000;
const gasTradingLimit = 250000;
const gasPrice = 5;

const getAllowance = async (tickerTokenAddress, thisWalletAddress, liquidtyPoolRouter) => {
    var contract = new web3.eth.Contract(abi, tickerTokenAddress);
    let approvalLimit = await contract.methods.allowance(thisWalletAddress, liquidtyPoolRouter).call();
    let decimals = await contract.methods.decimals().call();
    // this comes back with 3 variables, an approval, an approval in token units and the decimals
    return [approvalLimit, approvalLimit / (10 ** decimals), decimals];
}

const getApproval = async (thisTokenAddress, approvalAmount, thisDecimals, walletAccount, liquidtyPoolRouter, thisGasPrice = gasPrice, thisGasLimit = gasApprovalLimit)  => {
    console.log(`getting approval`);
    let contract = new ethers.Contract(thisTokenAddress, abi, walletAccount);
    let approveResponse = await contract.approve(
        liquidtyPoolRouter, 
        ethers.utils.parseUnits(approvalAmount.toString(), thisDecimals),
        {
            gasLimit: thisGasLimit, 
            gasPrice: ethers.utils.parseUnits(thisGasPrice.toString(), 'gwei')
        });
    console.log(approveResponse);
}

const swapExactBNBForTokens = async (buyAddress, buyDecimals, tokensIn, tradeSlippage, thisGasPrice = gasPrice, thisGasLimit = gasTradingLimit) => {
    let amountIn = ethers.utils.parseUnits(tokensIn.toString(), buyDecimals);
    let amounts = await routerV2.getAmountsOut(amountIn, [wbnbAddress, buyAddress]);
    let amountOutMin = amounts[1].sub(amounts[1].mul(tradeSlippage).div(100));
    let tx = await routerV2.swapExactETHForTokens(
        amountOutMin,
        [wbnbAddress, buyAddress],
        walletAddress,
        Date.now() + 1000 * 60 * 10,
        {
            value: amountIn,
            gasLimit: thisGasLimit, 
            gasPrice: ethers.utils.parseUnits(thisGasPrice.toString(), 'gwei')
        }
    )
    console.log(`Transaction Submitted...`);
    let receipt = await tx.wait();
    console.log(receipt);
}

const swapExactTokensForBNB = async (sellAddress, sellDecimals, tokensIn, tradeSlippage, thisGasPrice = gasPrice, thisGasLimit = gasTradingLimit) => {
    let amountIn = ethers.utils.parseUnits(tokensIn.toString(), sellDecimals);
    let amounts = await routerV2.getAmountsOut(amountIn, [sellAddress, wbnbAddress]);
    let amountOutMin = amounts[1].sub(amounts[1].mul(tradeSlippage).div(100));

    let tx = await routerV2.swapExactTokensForETH(
        amountIn, 
        amountOutMin,
        [sellAddress, wbnbAddress],
        walletAddress,
        Date.now() + 1000 * 60 * 10,
        {
            gasLimit: thisGasLimit, 
            gasPrice: ethers.utils.parseUnits(thisGasPrice.toString(), 'gwei')
        }
    )
    console.log(`Transaction Submitted...`);
    let receipt = await tx.wait();
    console.log(receipt);
}

// USAGE
// swapExactBNBForTokens(bunnyAddress, 18, 0.3, 2); // spending 0.3 BNB to buy BUNNY
// swapExactTokensForBNB(bunnyAddress, 18, 3, 2); // spending 3 BUNNY to buy BNB
getAllowance(bunnyAddress, walletAddress, pcsRouterV2).then((value) => {console.log('V2 ' + value);});

Answer 1

这是您在 failed 中提供的 amountIn tx: 3299718614161746000.

这是您在成功 tx: 3299718614161745787中提供的amountIn，它是更少。

所以我假设您提供的 amountIn 不正确，它大于您的余额。

Web3/nodejs 无法在 Pancakeswapv2 上使用 swapExactTokensForEth

Web3/nodejs not working with swapExactTokensForEth on Pancakeswapv2

node.js

web3js

binance-smart-chain